My 1998 V70 NA engine dropps a cylinder every now and then. I brought the car to my dealer last summer to be checked when this started and they could find nothing wrong. I bought Plugs, wires, cap, rotor, fuel filter, air filter from them. I cleaned the throddle body, checked vacuume hoses (replaced the questionable ones) No check engine light. Still mostly at idle in gear it bumps once than is fine for a while. It happens while driving on the interstate and feels like the compressor cycled even with the a/c off. I also cleaned the mass airflow meter with proper cleaner. Nothing changes it except to be sure I did not have water in the gas I ran one tank to 50% alcohol and it ran smoother than ever and never missed once till I filled it back with premium. Could I have a questionable injector? How to find it since it hapens so rarely? I did change the fuel filter again after the alcohol in case trash broke loose from the tank. The filter was clean. Does anyone have any ideas?